Relay construction



Oct. 8', 1946. F. n. ncaERl-Y RELAY GOHSTRUCI'IUI Original Filed July 29, '19,

Patented Oct. 8, 1946 RELAY CONSTRUCTION I Frank R. McBerty, Mansiield, Ohio, assignor toA The North Electric Manufacturing Company,

Galion, Ohio, a corporation i'y Ohio Original application July 279, A. Y1940, Serial N o. 348,222. Divided and this application June 28, 1943, Serial N0. 492,568

My invention relates, generally, to the construction oi relays for automatic telephone exchanges and it has particular relation to the construction of the stationary contact members thereof.v This application is a division of my copending application Serial No. 348,222, filed July 29, 1940.

The various limitations, costs, defects and failures of automatic exchanges are well known and throughout many years have been the objects of much study, research and invention. They concern the volume and cost of the equipment and its housing, the inadequate speed of operation, electrical interference with or disturbance of the Voice currentsarising within the switching structure, the power and the destructive effects 0f its operation, deterioration during the life 0f many years of uninterrupted operation, changes of structure resulting from abrasion, deformation, stress, corrosion, loss of insulation, changes of speed and timing of movement of parts,

During the life of the equipment, the various factors of change and deterioration require attendance, inspectionfand test, replacement, repair, adjustment and ultimately total replacement for inoperativeness rather than substitution oi" radically improved structures, Having in mind these limitations and defects, I have aimed t0 produce an automatic central-office exchange equipment, compact, unchanging within the limits of necessary operation, durable, simple, utilizing small forces, parts of minimum mass, incapable of adjustment; and have thereby attained speed of action, freedom from internal electrical disturbance and destructive eiects, the exclusion of attendance, inspecting, testing adjusting, and repair to a degree not heretofore found in any type of automatic exchange. vThe compact character permits reduced housing space and cost, combined with reduced hazard .of damage; the exclusion of attendancereduces the cost of operation, the hazard of unskilled handling, tamperingland sabotage. y

To this end, my invention comprises certain new types of electro-magnetic switching devices,

s Claims.v l(o1. o-104)y certain wiring structures for interconnecting the parts, new forms and compositions of material, and certain methods of utilizing the severalmaterials and producing the desired structures as hereinafter described.`

For a more complete understanding of the na-l l rits withtlie, U-shaped magnetic member com- Figure 1 is a view, in side elevation, certain parts having been broken away to more clearly show the details of construction, illustrating one embodiment of my improved relay construction assembled as a part of a line finder or connector link of an automatic telephone exchange of the relay type;

" Figure 2 is an end view of the construction shown in Figure 1, certain parts being shown in section;

Figure 2A is a sectional View, similar to Figure 2, showing in more detail the arrangement of the magnetic circuit;

Figure 3 is a plan view, at an enlarged scale, showing the arrangement of one set of movable and stationary contact members;

Figure ,4 is a longitudinal sectional View taken along the line 4-1l of Figure 3; and

Figure 5 is a detail sectional View taken along the line 5 5 of Figure 4. Referring now particularly to Figures 1 and 2 of the drawing, it will be observed that the reference characters I9 and Il each designate, generally, a relay construction. Each of these relay constructions may comprise what is known in the telephone art as a tens relay, ten of which are mounted in alignment to provide the tens relay cfa line finder or connector link, as is disclosed in more detail in my copending application Serial No. 348,223, iiied July 29, 1940. Since the construction oi the relays iii and l I is identical, only one of them will be described in detail herein.

These relays are designed for use in connection with the'type oi' automatic selective system for automatic telephone exchanges known as the All-relay system, of which the selective structureand its inode of operation are described in Telephone Theory and Practice, by Kempster B, Miller, first edition, 1933, chapter VI.

As shown in Figures 2 and 2A of the drawing, eachjrelay is provided with a magnetic circuit which may be that of an electromagnet having a broad pole piece with a suitable magnetic return. The toward pole piece may take the form of YaT and the return pole piece may have the form of, an intertting U member comprising side plates i2 and the back-bar I3.

The two-sided magnetic structure is designed toreceive'on each of its sides, groups or armatures whereby the groups of armatures are acted upon by substantially equal portions of the flux generated'in the core and thereby respond in substantially equal acts to equal forces'.r

The T-shaped magnetic member which nterprises a pole piece I4 and a core I5. The core I5 comprises the stem of the T and around it is positioned a winding or coil I6 of conventional design. The core I5 may be secured to the back lbar I3 and the pole piece I4 by press fits, if it is not desired to provide for ready removal of the coil I0. If it is desired to permit ready removal of the coil I6, then the pole piece I4 should be arranged to be readily detached from the core I5 or the core I5 should be arranged to be readily detached from the back bar I3.

The pole piece I4 is of such material and climansions with relation to the U-shaped member, the core I5 and the coil I6 that the flux generated by the coil is as nearly as possible equally distributed Ibetween the two sides of the pole piece and throughout the length of each side.

It will be observed that air gaps I1 are pro-- vided between the ends of the U-shaped magnetic member formed by the side plates I2 and the back bar I3 and the ends of the top of the T-shaped magnetic member formed by the pole piece I4 andthe core I5. These air gaps are preferably about 55s inch long. However, these air gaps bear a certain necessary relation to the size and material of the armatures and their proximity to the pole piece, as will be fully described later.

With a view to accurately aligning the side plates I2 oi the U-shaped magnetic member with the pole piece I4, clamp plates are provided on opposite sides of the side plates I2 and are secured in position by means of screws 2I which are threaded into the ends of strut members, one of which is shown at 22. 1t will be observed that the strut members 22 serve not only to provide a clamping action between the upper ends of the clamp plates '20, but also that they serve to space them and the side plates I2 apart.

Positioned on top of 'the pole piece I4 and common to both of the relays I0 and Il is an insulating block 23 which is secured in position by screws, one of which is shown at 24, which project through the pole pieces I4 and into the upper threaded end of a strut member 25, the lower end of 'which is threaded into the back bar 13. The insulating block 23 is preferably formed cf moul'dable material, such as a thermoplastic. Along the edges of the insulating block 23 are moulded contact members 2G which form the stationary contact members of the relays. As is shown more clearly in Figure 4 of the drawing, each of the contact members 23 is provided with a reentrant portion 21 about which the material forming the insulating block 23 is moulded to securely grip the contact members in position.

Referring again to Figures 1 and 2 of the drawing, it will be observed that the contact members 26 are provided with extensions 26a, 2Gb, 26e, 26d, etc. The Vextensions 26a, 26D, 26d., etc., are arranged in staggered relation of decreasing lengths and their upper ends are turned outwardly as indicated at 28 and notched as indicated at 20. This staggered arrangement of the extensions is provided in order to facilitate connection thereto of paralleling conductors which can then be positioned in coplanar relation. As is described in detail in my copending application Serial No. 348,223, referred to hereinbefore, corresponding extensions 20a of the relays I0 and II are connected in parallel circuit relation by a Wire which is secured in the notched portions 29 `by being spot welded therein.

It will be observed that the upper ends 28 of the extensions 26o are turned inwardly rather than outwardly as is the case respecting the other extensions. This construction is employed since these extensions are not paralleled with any other extension ci' any other relay in the link. In order to permit the conductors connected to extensions, such as the extensions 26C, with conductors arranged in coplanar relationship, these extensions on the several relays are staggered by having the upper end portions 28 of diierent heights.

It will also be observed that the extensions 20a, 26?), etc., on one side of the insulating block 23 are offset with respect to the corresponding extensions on the other side. The purpose of this offset relationship will be presently apparent.

The contact members .26 and their extensions are formed of good conducting nontarnishing material such as German silver. In the embodiment 'of the invention shown in the drawing they are 0.080 inch wide and alf inch thick. The lengths of course vary depending upon the length or the extension individual thereto.

Individual to each of the anvil contact members 2G, there fis provided a contact ringer which is designated generally at 32. Each contact ilnger 32 comprises a metallic reed 33 in the form of round wire which has good electrical conducting quality and is highly resilient and corrosion resisting. I have found that stainless steel wire, known lil-S, and having a diameter of 0.016 inch, is highly satisfactory for my purposes.

y Mounted on the upper end 34 of each ci the metallic reeds 33 is an armature 35 which serves not only to iiex the metallic reed 33 on energical tion of lthe winding I6 but also it serves to conthat an air gap of 0.032 inch is provided therebetween. yIt is possible to increase this air gap to 0.053 inch but the smaller air gap is preferable. When the armature 35 has been moved into its alternate position on energization of the coil I5, there is provided a residual air gap between the armature 35 and the adjacent edge of the pole piece I4 of from 0.010 to 0.012 inch. It will then be apparent that the movement of the armature 35 from one position to another is about 0.020 inch.

The armatures 35 are formed of material which not only has good electrical conducting properties but also material which is magnetic. I have found that material known as Allegheny metal No. 4750 is entirely satisfactory for this purpose. Each of the armatures 35 is preferably about 0.478 inch long, about 0.080 inch wide and about 0.0429 inch thick.

The lower ends 33a 'of the metallic reeds 33 project beyond insulating support members 31. The insulating support members S1 are formed of the same material as the insulating block 23 and, as will hereinafter appear, the metallic reeds 33 are especially prepared so as to make certain r that they will lbe securely held in the insulating support members 31 on completion of the moulding operation.

Referring to Figure 1 of the drawing, it will be observedthat the projecting lower ends 33a, 33h. etc., of the metallic reeds 33 extend downwardly through 'the same distances. It will also be observed that the lower ends 33a, 3312, etc., on one side of the relay construction are offset with respect to the corresponding lower ends 33a, 33h, etc., on the other side. This arrangement is proreferred to hereinbefore.

` vided in order to permit the coplanar arrangement of cross connecting conductors between corresponding tens relays of adjacent links as is described more fully in my copending application, The cross connecting conduetors'are secured by suitable means, such as welding, to the lowermost portions of the projecting lower portions 33a, 33h, etc. Since these projecting portions are staggered, the cross connecting conductors can obviously be arranged in a single plane, as described. Since the contact members 26 are arranged in alignment with their respective contact fingers 23, the reason for the offset positions of the contact members 26 on the opposite sides of the insulating block 23 will now be apparent. l

The insulating support members 31 in which are moulded the metallic reeds 33 may be secured in position on the back bar I3 by means of screws 38. These screws also serve to carry support members 39 which are arranged to support conductor brackets carrying conductors extending underneath the relays l0 and ll. As is set forth in detail in my copending application Serial No. 348,223, referred to hereinbefore, certain of the downwardly extendingends 33a, 33h, etc., of the metallic reeds 33, are arranged to be connected in parallel in their respective links, while the remaining downwardly projecting end portions are arranged to be cross connected as described.

As shown more clearly in Figures 3, 4 and 5 of the drawing, each of the armatures 35 is provided with an erosion resisting contact member 4| in the form of a short length of round wire. The contactk member 4| is preferably formed or good conducting material which will resist erosion due to abrasion and arcing. I have found that round wire formed of palladium is satisfactory for this purpose. A wire having'a diameter of 0.020 inch and a length of about 0.070 inch of this material is welded, as shown, across one face of the armature 35 to provide the contact engaging surface thereof.

Each of the contact members 25 is likewise provided with erosion resisting material. As shown,

this comprises an insert 42 in the lower end of each of the contact members 2S. The inserts 42 may be formed of palladium and are inlaid by conventional means in a strip of German silver from which the contact members and their integral extensions are cut. The insert 42 is preferably about ea inch wide and about 0.010 inch thick. As indicated at 43, each of the inserts e2 is grooved intermediate its ends so as to provide two distinct points of'contact engagement with the generally cylindrical contact member 4I carried bythe armature 35. In the event that the alignment between the armature 35 and the contact member 26 is not such as to initially cause both contact engagements to take place, it will be obvious that the armature 35 will be turned slightly due to the pull of the flux generated by the coil I3 so as to cause the two point Contact engagement as described.

The lower end of the stationary contact conductor 26 is free of the backing of the insulating support 23, as will be seen in Figures 2, 3 and 4. This avoids the danger of clogging the contact portions with insulation, and it leaves the' free portion of the stationary contact conductor 26 of such short length that its natural period of vibration is extremely high.

It is highly desirable that the armatures 35 associated with each side of each of the relays l0 and H be accurately aligned so that uniform air anvil.

6 gaps are provided between them andthe adja cent edges of the pole pieces I4. For this purpose, as shown in Figure 2 of the drawings, the metallic reeds 33 are so arranged that they tend to bias the armatures 35 outwardly to a position beyond the normal open circuit position.

The stop member 44 of suitable, hard, rigid and non-hygroscopie material such as Pyrex glass, is positioned along the armature 35, and is so 1ocated that the inherent resilience of the Ametallic reeds 33 urge the armature into engagement therewith. The glass rods 44 are held in position by means of suitable non-magnetic clamp members 45 which are held in place by the screws 2l. t is the common experience in apparatusof the types herein under consideration that the resting anvils upon which spring points, levers and armatures normally rest under more or less pressure are subject .to various changes which alter the positions of the resting parts and .delay or stop their operation. The metals and some insulating material used yield under the hammering of the return strokes of the. parts and alter the position of rest and consequently the operating adjustment. Moisture is deposited upon the surfaces which affects the material chemically, or in the case of sudden loweringof temperature, may actually freeze the parts.y in their resting position; oxides and impalpable metallic powders form; dust accumulates; the moisture when present consolidates these extraneous materials into adherent scales or adhesive cements, the deleterious action of whichv is increased as the contacting surfaces are hammered down into close fitting surfaces; These; effects disturbing to the operation, vary with temperature, moisture and frequency of operation and require a large factor of safety in the forces re quired to move the movable part from its resting In the course of a relatively short' period, such parts require cleaning and in the meantime, increasingly frequent and irregular failures of operation may take place. The moving partsarmatures and reeds-in the invention here de scribed, bear upon their resting anvils with slight force, merely enough to x accurately tbeposition of rest, and are intended to be operated upon by minimum attractive forces, since by these means the energy consumed by the device and the detrimental and destructive effects of the motion are reduced to a minimum and the speed of operation is increased.

The stop-rod 44 of Pyrex or equivalentglass, is straight, inflexible, unchanging under normal temperatures; it is not deformed by the impact of the parts resting upon it; it suffers no chemical change, accumulates no moisture or dust, it changes temperature slowly and does not freeze the armatures; and in no way injuriously affects the metal parts resting upon it. In fact, the operation of the armatures hundreds of millions of times, equivalent to thousands of years of commercial operation, exhibits practically no alteration in the characteristics of operation. It must be assumed that the impact of the returning armature upon the glass rod must expend in heat its energy of motion and must create some vibration; but it is found that the period of vibration is of such high frequency and so brief as to be hardly detectable in a cathode ray oscillograph.

Not only do the glass rods or stop members 44 align the armatures 35 so that uniform air gaps are provided, but also they serve to prevent oscillation of the armatures 35 on the deenergization of the coil I6. As soon as the armatures 35 em ent embodiments of `the invention can be made Without departing from the `scope thereof, it is intended that all matter contained in the above description or shown inthe accompanying drawM ing shall be interpreted as illustrative and not in `a'limiting sense.

I claim as my invention:

1. A stationaryz contact assembly comprising a series of closely spaced flat metallic stripshav ing body portions disposed edge to edge substantially inthe same plane, said strips having their lower ends disposed on substantially the saine level, and their upper ends disposed at 'different levels and extending laterally out of said plane,

erosion resisting contacts mounted on the strips at their lower ends, saidstrips having looped porM tions in alignment adjacent said lower ends and a supporting block of insulation having a face thereof disposed substantially in the plane of said strips and 'having integral portions moulded around and extending over said loops for holding the strips in fixed position.

2. A stationary contact assembly comprising a series of closely spacedthin at metallic strips having their lower ends aligned edge to edge on the same level, contact points on said aligned lower ends, a supportingblock of insulation naving a face lying substantially iush with the front faces of the lower ends of said strips, said strips having offset Vportions above the Contact points disposed withinl and moulded in the body of in sulation to hold the strips in xed positioirand having upwardly extending portions providing terminals.

3. A stationary contact assembly comprising a series of thin nat metallic strips having their lower ends disposed in parallelism edge to edge, contacts of erosion resisting metal mounted on said lower ends, a flat block of insulation forming a support for said strips, said blockhaving an edge face Vsubstantially ilush with the outer sur.- i'aces of said lower ends of the metallic strips, each of said strips having a part of its` length offset into and embraced by and moulded in the material of the block of insulation and having an upwardly extending terminal portion.

4. A Contact member for a, multiple relay comprising a flat sided strip of tarnishresisting metal having a plate of precious metal upon the flat face at its lower end, said plate of precious metal being inset to besubstantially flush with the face of the strip and having a groove extending longitudinally of `the strip, the strip having a lateral loop adjacent its lower end forming an anchorage by which the member is adapted to be supported and having a laterally oiset terminal portion at its'upper end; said terminal portion having a notch for locating a connecting wire.

5. The contact of claim 4 wherein the strip is formed of German silver and lthe lcontact plate oi palladium.

6. Multiple contact arrangement comprising a stationary contact element, a ilat narrow metallic strip fixedly supported in insulated relation, a contact plate of erosion resisting metal clad upon the face of the lower endY thereof, a groove formed in said contact'plate to provide ridges on opposite sides of the groove, a cooperating movable contact element cooperating with said stationary contact element, said `movable contact element comprising a narrow rigid metallic armature aligned longitudinally with said strip and having its inner end overlapping said contact plate, a slender spring wire reed-upon the outer end of which said armature is rigidly attached in longitudinal alignment, andra short piece of iine contact wire of an erosion resisting metal welded upon and across the upper overlapping end of the armature and lying transverse to the aforesaid ridges on the stationary contact, said wire reed being adapted to be ilexedlongitudinally to bring said contact Wire into engagement with said contact plate and adapted to be twisted iii-necessary to secure engagement of said contact wire with both ridges when the movable contact element is urged toward the stationary contact element.

7. Contact means comprising a series of coplanar edge to edge metallic strips of graduated length, said strips havingtheir lower Contact ends disposed in alignment and having looped portions extending out of the plane of the bodies of the strips, a bar of insulation moulded about said loops and substantially flush with the outer faces of the strips and leaving the lower contact ends and the upper ends of said strips free.

8, The contact assembly of claim 2,-wherein the upwardiy extending portions have laterally extending terminal portions of substantially equal length lying at spaced levels above said block, and said laterally extending terminal portions have their ends grooved to provide seats for receiving bare wire conductors.

`FRANK R. MCBERTY. 

